JP2003316205A - Image forming apparatus - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To prevent images from flowing under a high humidity environment. <P>SOLUTION: Electric energy to be supplied to a heater is controlled (increased) for fixed time (number) after energization is on according to time without any energization to the heater, concretely speaking temperature increase, start-up is increased with temperature being equal, energization to the heater that is not used normally, and the like. Additionally, temperature/moisture when the energization is turned on or off, and further the type of a transfer material to set paper may be combined for control. <P>COPYRIGHT: (C)2004,JPO

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an image forming apparatus such as a copying machine, a printer or a facsimile which forms an image by an electrophotographic method.

[0002]

2. Description of the Related Art FIG. 7 is a schematic configuration diagram showing an example of an image forming apparatus (a copying machine in this conventional example) for forming an image by a conventional electrophotographic method.

This image forming apparatus comprises a drum type electrophotographic photosensitive member (hereinafter referred to as a photosensitive drum) 1 as an image bearing member.
Further, a primary charger (corona charger) 2, an exposure device 3, a developing device 4, a transfer charger 5, a separation charger 6, a cleaning device 7, and a pre-exposure lamp 8 are provided around it.

The photosensitive drum 1 is a negatively charged organic photosensitive member in this conventional example, has a photosensitive layer (not shown) on an aluminum drum base (not shown), and is arranged in the direction of the arrow (clockwise). It is rotationally driven at a predetermined peripheral speed (process speed).

The primary charger 2 uniformly charges the surface of the photosensitive drum 1 with a predetermined polarity and potential by corona ions generated by corona discharge.

The exposure device 3 applies a laser beam (image exposure) L according to the input image information (image signal) to the surface of the photosensitive drum 1 which has been charged by the primary charger 2. The electrostatic latent image corresponding to the image information input to the surface of the photosensitive drum 1 is formed by the image exposure by the laser light L emitted from the exposure device 3.

The developing device 4 includes a rotatable developing sleeve 9
As a result, toner is attached to the electrostatic latent image at the developing position to visualize it as a toner image.

Next, the image forming operation of the image forming apparatus will be described.

During image formation, the photosensitive drum 1 is rotationally driven by a driving means (not shown) at a predetermined process speed in the direction of the arrow, and the surface thereof is uniformly charged to, for example, -700V by the primary charger 2. Image exposure L is performed by irradiating the charged photosensitive drum 1 with laser light from the exposure device 3.
Is given to form an electrostatic latent image according to the image information of the input document (not shown). Then, toner is attached to the electrostatic latent image by the developing sleeve 9 to which a developing bias having the same polarity as the charging polarity of the photosensitive drum 1 is applied,
It is developed as a toner image.

When the toner image on the photosensitive drum 1 arrives at the transfer nip portion N between the photosensitive drum 1 and the transfer charger 5, the registration roller pair 17 adjusts the timing to feed the paper cassettes 10, 11, 12 or. Bypass tray 1
The transfer material P selected from 4 and fed is conveyed to the transfer nip portion N, and is transferred onto the surface of the transfer material P by the transfer charger 5 to which a transfer bias having a polarity opposite to that of the toner is applied. The toner image is transferred.

Transfer materials P having different sizes are stored in the paper feed cassettes 10, 11, and 12, and each transfer material P is transferred by the paper feed rollers 13a, 13b, 13c.
Sheets are fed one by one and conveyed by the conveying rollers 15a, 15b, 15c to the registration roller pair 17 through the conveying guide 16. Further, a transfer material of any size can be stored in the manual feed tray 14, and can be transported to the registration roller pair 17 by the transport roller 19.

The transfer material P, onto which the toner image has been transferred at the transfer nip portion N, is weakened in electrostatic attraction between the transfer material P and the photosensitive drum 1 by the separation charging device 6 and thus the photosensitive drum 1
After being separated, the toner image is conveyed between the fixing roller 18a and the pressure roller 18b of the fixing device 18, and the toner image is thermally fixed on the surface of the transfer material P by heating and pressing by the fixing roller 18a and the pressure roller 18b and discharged. To be done.

In the case of double-sided image formation or image formation in the multiple image formation mode, after the image formation on the first side of the transfer material P is completed and the image passes through the fixing device 18, the image is again registered through a path (not shown). The sheet is fed from the roller pair 17 to the transfer nip portion N.

The transfer residual toner remaining on the surface of the photosensitive drum 1 after the transfer of the toner image is removed and collected by a cleaning device (cleaning blade) 7, and the residual charge on the surface of the photosensitive drum 1 is pre-exposure lamp. It is removed in step 8 to prepare for the next image formation.

Environmental conditions such as temperature and humidity are variously changed depending on the season, the weather, the structure of the building, the condition of the air conditioner, etc., in the place where the image forming apparatus is installed and used.

Especially in a low temperature environment such as winter, the main body power source OF
Since the parts inside the image forming apparatus left in the F state for one night or more are completely cold, dew condensation may occur immediately after the power is turned on.

Separately from this, by repeating the image forming process such as charging exposure development, transfer and cleaning for a long period of time, the surface of the photoreceptor becomes sensitive to humidity and water is easily adsorbed on the surface. As a result, the surface resistance decreases, and the surface charge moves laterally, which causes a problem of so-called image deletion in which an image is blurred.

This phenomenon is remarkable when the humidity is high. The reason for this is that the corona discharge used in the primary charger, the transfer / separation charger, or the auxiliary charger mainly used to assist the charging of the developer between the development and the transfer and between the transfer / separation and the cleaner. It is considered that ozone and discharge products generated by electric appliances adhere to the surface of the photoconductor, resin or additives contained in the developer or additives contained in the transfer paper, and this adheres moisture. There is.

Therefore, in the prior art, in order to avoid the above-mentioned problems, a heater is provided inside or in the vicinity of the photosensitive drum to heat the photosensitive drum so as to suppress the adsorption of moisture on the various adhered substances and prevent the occurrence of image deletion. Measures are being taken.

[0020]

However, the above-mentioned conventional example has the following problems.

Normally, the user often turns off the power of the main body when the frequency of image formation is extremely low or at night, but when the power is turned on again and the device is used again, it is ready for use. It is widely used that the energization of the drum heater is set independently of ON / OFF of the main body power supply. Further, the above configuration is also necessary for shifting from the standby state of the FAX multifunction machine to the printing after reception.

However, the energization of the heater is not supplied in the following situations.

Not all image forming apparatuses are designed as described above, and there may be ones in which the power supply to the main body and the power supply to the heater are interlocked, for example, with safety as the first priority.

When the power plug is pulled out at night or on holidays when the main body is not used. From the standpoint of reducing standby power consumption and energy saving, or in order to secure safety when the user is absent, it is conceivable that the power plug will be unplugged, but in this case, no power is naturally supplied to the heater.

Especially at night or on holidays, the air conditioner in the room in which the main body is installed is often stopped, and the temperature becomes low in winter, so that the photosensitive drum is liable to be condensed when the main body is powered on as described above. In addition, the temperature and humidity increase in the summer, and moisture is likely to be adsorbed on the surface of the photosensitive drum.

Even in the above situation, even if the power supply to the drum heater is turned on and the power supply to the drum heater is started, there are the following two problems.

1) Since it takes time for the surface of the photosensitive drum to rise to a predetermined temperature after the energization of the drum heater is started, problems such as image deletion may occur when image formation is performed during that time. There is a nature.

2) A larger amount of water is adsorbed on the surface of the photosensitive drum immediately after the heater energization is turned on, as compared with the case where the energization on state continues. Therefore, even if the temperature of the photosensitive drum surface rises relatively quickly, problems such as image deletion are likely to occur.

Therefore, the present invention has been made in view of such a situation as described above, and it is judged that there is a possibility that a large amount of water is adsorbed on the surface of the photosensitive drum or dew condensation occurs because the photosensitive drum heater is not energized for a certain time or longer. Power is on when
The purpose is to prevent or reduce the occurrence of image defects such as image deletion by strengthening the power supply to the photosensitive drum heater for a predetermined time after N.

[0030]

To achieve the above object, the first invention of the present application is directed to an image carrier, a charging means for charging the image carrier, and a charged surface of the image carrier. Exposure means for forming an electrostatic latent image according to image information by imagewise exposure, developing means for forming a toner image by adhering toner to the electrostatic latent image, and transferring the toner image at a transfer portion. In an image forming apparatus having a transfer means for transferring to a material and a heater for heating the image carrier inside or in the vicinity of the image carrier, the energization is turned on depending on the time when the heater was not energized in the previous period. It is characterized in that the amount of electric power supplied to the heater is controlled for a predetermined time after the start.

The second aspect of the invention is to control the average amount of electric power per unit time supplied to the heater for a predetermined time after the energization is turned on, according to the time when the heater is not energized. Characterize.

A third aspect of the invention is characterized in that the temperature of the heater is controlled for a predetermined time after the energization is turned on according to the time when the heater is not energized.

Further, the fourth invention is characterized in that the temperature of the heater is set higher than usual for a predetermined time after the energization is turned on, depending on the time when the heater is not energized.

With the above structure, when the power supplied to the heater is turned on or the power to be supplied is increased or the power is repeatedly controlled to be turned on and off, the ratio of the on time is increased to supply the power per unit time. By increasing the amount, it is possible to raise the temperature of the heater, or to energize another heater that is not normally used even at the same temperature to raise the drum surface temperature faster and maintain it at a higher temperature. It will be possible. Therefore, removal of water on the surface of the photosensitive drum can be promoted, and image deletion can be prevented or suppressed.

The fifth aspect of the present invention is based on both the time when the heater is not energized and the temperature / humidity data in the vicinity of the image carrier or in or near the image forming apparatus, after the energization is turned on. The amount of electric power supplied to the heater for a predetermined time is controlled.

With the above configuration, the amount of electric power supplied to the heater is controlled by utilizing the temperature and humidity data inside or near the image forming apparatus. Therefore, for example, in a low humidity environment, the amount of water adhering to the surface of the photosensitive drum is small and the image flow occurs. When the power supply does not occur, the power supply amount can be controlled not to be strengthened or to be turned off. Therefore, strengthen the photosensitive drum heater only when it is necessary under temperature and humidity conditions, and turn it ON / OF.
Since the F control can be performed, it is possible to reduce wasteful power consumption and prevent adverse effects such as temperature rise in the machine.

The sixth aspect of the invention is characterized in that the temperature / humidity data is one or both of the history of the state where the energization is OFF and the time when the electricity is turned ON.

With the above structure, when temperature / humidity data at the time when the power is turned on is used, there is an advantage that no memory is required and the control can be simplified.

On the other hand, when using history data of temperature and humidity when the energization is OFF, a memory for storing the data and a processing process are required, but the amount of power supplied to the photosensitive drum heater is more appropriate. Can be controlled. For example, when the air conditioner in the room in which the image forming apparatus main body is installed is also stopped at night or on a holiday, the temperature and humidity are often high in the summer. At this time, if the air conditioner is turned on and the power of the image forming apparatus main body is turned on after a while, the amount of adsorbed water on the surface of the photosensitive drum is still changing even if the temperature and humidity are normal values. Since it is not present, image deletion may occur. In such a case, it is possible to solve it by using history data of temperature and humidity.

According to the seventh aspect of the invention, depending on the time when the heater is not energized and the type of the transfer material to be fed,
It is characterized in that the amount of electric power supplied to the heater is controlled for a predetermined time after the energization is turned on.

The state of occurrence of image deletion is
It also changes depending on the type of transfer material used. Therefore, by controlling the amount of power supplied to the heater based on both of them, it is possible to minimize power consumption and adverse effects and prevent / suppress image deletion.

According to the eighth aspect, the energization is turned on depending on the combination of the time when the heater is not energized and the selected transfer material accommodating section among the plurality of transfer material accommodating sections. It controls the amount of electric power supplied to the heater for a predetermined time.

By registering the types of the transfer material to be stored in the plurality of transfer material storage portions, the type of the transfer material can be discriminated from the selected transfer material storage portion, and the above-mentioned method can be used without a mechanism for detecting the type of the transfer material. The same effect as can be obtained.

[0044]

BEST MODE FOR CARRYING OUT THE INVENTION (First Embodiment) This embodiment is applicable to the image forming apparatus shown in FIG. 7, and the basic image forming operation is as described above. here,
The photosensitive drum heater unit and control will be described.

FIG. 8 shows a cross section of the photosensitive drum 1, in which a photosensitive drum heater 20 is arranged. A flange 22 is attached to the rear end of the photosensitive drum 1 as shown in FIG. 9, and power is supplied to the photosensitive drum heater 20 by sliding a contact 23 attached to the main body of the image forming apparatus. .

Various types of photosensitive drum heaters 20 can be used. For example, it is possible to use one in which a wire having an appropriate resistance is sandwiched between resin sheets, or one in which metal powder, carbon, or the like is mixed with a binder as shown in FIG. In FIG. 10, 20a is a resin sheet and 20b is a printed comb-shaped electrode.

The drum surface temperature is measured by a temperature sensor 21 arranged in the vicinity, and the power source for the photosensitive drum heater is controlled via the bias controller so as to reach a predetermined temperature.

In the image forming apparatus having the above structure, in this embodiment, the energization of the photosensitive drum heater is controlled as shown in the timing chart of FIG.

That is, the photosensitive drum heater is kept at 40 ° C. during the image forming operation from t _{0 to} t ₁ or during standby.

The drum heater shows the control of this embodiment. When the main body power SW is turned off at t ₁ and the power plug is also unplugged at the same time, the power supply to the photosensitive drum heater 20 is stopped. For example, if the apparatus is left in a state where the energization is stopped at night, not only the photosensitive drum heater 20 but also the entire image forming apparatus cools and approaches the room temperature. Therefore, even if the power plug and the main body power SW are turned on in the morning of the next day, the surface temperature of the photosensitive drum does not reach the predetermined temperature for a while. If the image forming operation is performed from this state, an image defect such as image deletion will occur due to the reason described above. Therefore, by controlling the temperature control temperature to be 48 ° C. only during the period from t _{2 to} t ₃ , the water adsorbed on the surface of the photosensitive drum can be quickly removed to prevent or control the image deletion. After the water is sufficiently removed, the normal control is resumed and the controlled temperature is set to 40 ° C. The set temperature at this time is a matter to be determined by the image forming apparatus, but 40 ° C. in the normal state in the present embodiment is a temperature sufficient to prevent / suppress image defects such as image deletion in a normal use state, 48 ℃
Is the upper limit temperature at which the toner is not melted and coagulated or the toner is not fused on the photosensitive drum even at this temperature.

FIG. 2 shows the transition of the surface temperature of the photosensitive drum in the above control. At t ₀ ~t ₁ is kept at 40 ℃, _{t 1}
Gradually approaches room temperature. When the photosensitive drum heater is energized again at t ₂ , in the normal control, it rises as in the present embodiment.

[0052] As a modification of the (Second Embodiment) In the first embodiment, in which up to the maximum supply power both controlled temperature and at time t ₂ ~t _3. Since the surface temperature of the photosensitive drum changes as shown in FIG. 2 and rises earlier, the effect of the photosensitive drum heater can be obtained relatively quickly after the main body power is turned on.

As yet another example, at t _{2 to} t ₃ , the temperature control temperature is still 40 ° C. as shown in FIG. 1, but the supplied power amount is increased and the surface temperature is quickly raised. The transition may be controlled as shown in FIG. In this case, the surface temperature of the photosensitive drum rises to a predetermined temperature in a short time and is prevented from rising above a required temperature, which is effective in preventing the temperature rise of the entire apparatus. Therefore, even if images are continuously formed, problems such as toner solidification in the developing device or cleaner and toner fusion on the surface of the photosensitive drum are less likely to occur.

In this embodiment, as shown in FIG. 3, the main body power SW is turned off and the power plug is not pulled out, and the photosensitive drum heater is controlled independently of the main body power SW. The surface temperature of the photosensitive drum is always kept constant.

FIG. 4 shows the conventional control.

(Third Embodiment) In the present embodiment, the power supply immediately after the energization is turned on is controlled by the temperature and humidity while the energization to the photosensitive drum heater 20 is off. Assuming that the temperature and humidity during OFF are almost constant, control is performed based on the temperature and humidity when the power is ON.

FIG. 5 shows a time chart. Time t ₁ ~
The temperature and humidity when the main body power SW and the power plug are turned off during t ₂ are divided into three cases.
The control is performed as follows.

Case: In the case of high temperature and high humidity (27 ° C., 80%), it is judged that the image deletion is likely to occur immediately after the main body power is turned on at t ₂ , and the first and _{second operations} are performed between t ₂ and t ₃ . The power supply to the photosensitive drum heater is strengthened as shown in the above embodiment. Specifically, increase in temperature, increase in power consumption, or both.

Case: Normal temperature and normal humidity (23 ° C., 50%) Since the need for the photosensitive drum heater is moderate, the photosensitive drum heater is turned on at t ₂ according to normal control.

Case: At low humidity (20 ° C., 35%), the probability of image defects such as image deletion is low, so t ₂
Even if it becomes, it may remain off. However, since the sensitivity of the photosensitive drum has a slight temperature dependency, it may be turned on depending on the temperature (when the temperature is low) to stabilize the potential and the image density.

With the above structure, the amount of electric power supplied to the photosensitive drum heater is controlled by also utilizing the temperature and humidity data inside or near the image forming apparatus. Therefore, for example, in a low humidity environment, less water adheres to the surface of the photosensitive drum. If the image deletion does not occur, the power supply amount is not strengthened. Alternatively, control such as turning off can be performed. Therefore,
Strengthen the photosensitive drum heater only when necessary under temperature and humidity conditions.
Since N / OFF control can be performed, wasteful power consumption can be reduced and
It is possible to prevent harmful effects such as excessive temperature rise inside the machine.

(Fourth Embodiment) In the above-described third embodiment, it is assumed that the temperature and humidity are substantially constant while the energization of the photosensitive drum heater 20 is OFF, and the temperature inside or near the device at the time of energization ON. The subsequent power supply to the photosensitive drum heater 20 is controlled based on the humidity data.
However, the temperature / humidity environment inside or near the apparatus may change depending on the control state of the air conditioning equipment in the room where the image forming apparatus is installed and the temperature / humidity of the outside air. For example,
When the air conditioner in the room where the image forming apparatus main body is installed is also stopped at night or on holidays, it is often in a high-pitched, high-humidity state in the summer. At this time, when the air conditioner is turned on and the power of the image forming apparatus main body is turned on after a while, the amount of adsorbed water on the surface of the photosensitive drum has not changed yet even if the temperature and humidity are normal values. Therefore, image deletion may occur. Alternatively, when a temperature / humidity sensor is installed to measure temperature / humidity data near the image forming apparatus,
Even if the outside of the device is in normal temperature and humidity, the same problem may occur because the inside of the mounting is actually in a high temperature and high humidity state.

Therefore, in the present embodiment, control is performed based not only on the temperature / humidity data at the moment when the energization to the photosensitive drum heater 20 is changed from OFF to ON, but also on the temperature / humidity history data while the energization is OFF. By doing so, it is intended to prevent the above problems more accurately.

Description will be made with reference to the time chart of FIG.
Since the temperature / humidity state when the power supply to the drum heater 20 is OFF is simple, it is assumed here that there are two types of changes, and the following control is performed for each case.

Case: Initial 20 ° C., 35% → latter half 26 ° C., 70% In this case, the initial low humidity condition changed to the high humidity condition in the latter half, and therefore, immediately after the main body power was turned on (t ₂ ). Judge that image deletion is likely to occur. Between t _{2 and} t ₃ , as shown in the first and second embodiments, the photosensitive drum heater 2 is used.
Strengthen the power supply to 0.

[0066] Case: Initial 26 ° C, 70% → 23 ° C, 50% In this case, it was in a high humidity state at the beginning, but in the latter half it was normal.
During the medium humidity condition, the inside of the device also returns to the medium humidity condition.
In addition, the state of water absorption on the surface of the photosensitive drum returns to normal.
It is determined that Therefore, the need for a photosensitive drum heater
Medium, so t _TwoThe normal control is performed from.

[0067] Case: Initial 26 ° C, 70% → latter half 24 ° C, 35% In this case, since the low humidity continued in the second half, t_TwoTime point
The need for photosensitive drum heaters is low. Therefore, t_TwoSince
The descent may remain off. The case of the third embodiment is
Stability of the photosensitive drum and low image density
T for stabilization _TwoYou may turn it on.

The above description has been made on the assumption that the temperature / humidity state once changes while the energization of the photosensitive drum heater 20 is OFF. However, in reality, since the temperature / humidity state continuously changes, the temperature / humidity data is kept constant for a certain time, for example. You may make it take in every hour. Among them, the amount of water in each air is always calculated based on new data for 8 hours, and control is performed based on the simple average value, the average value weighted to the new data, and the average value considering the change rate. You may.

(Fifth Embodiment) The occurrence state of image deletion varies depending on the temperature and humidity conditions as well as the type of transfer material to be passed. That is, if the talc or other additive contained in the transfer material or the surface coating agent is easily attached to the surface of the photosensitive drum, image deletion is more likely to occur. Therefore, in the control shown in the above-described first to fourth embodiments, when a transfer material that easily causes image deletion is used, the heater is controlled so as to raise the temperature of the photosensitive drum, and the photosensitive drum is controlled. Control the temperature rise time for a longer period. ・ Turn on the photosensitive drum heater even under temperature / humidity conditions that are not normally turned on. -By controlling the above combinations, problems can be suppressed or prevented.

The transfer material to which the additive easily adheres to the photosensitive drum generally tends to have a large decrease in electrical resistivity in a high temperature environment, and therefore it can be identified by measuring the electrical resistivity of the transfer material.

As a means for measuring the electrical resistivity of the transfer material, a known method can be used in addition to the method of applying a bias to the registration roller pair 17 and the like to detect a current value when the sheet is passed.

(Sixth Embodiment) In Example 5, as an example of the method of detecting the transfer material in which the image deletion easily occurs, the method of measuring the electrical resistivity is shown.

In the present embodiment, in the case of an image forming apparatus having a plurality of transfer material storage portions, the amount of power supplied after the photosensitive drum heater is turned on by the selected storage portion is controlled. Therefore, the means for measuring the electrical resistivity of the transfer material is unnecessary. An example of a specific method will be described below.

As shown in FIG. 7, (1) three cassettes 10 to 12 are provided as transfer material storage portions.
In the case of the image forming apparatus having the above, the transfer material that easily causes the image deletion is registered in advance in the cassette 10. When the cassette 10 is selected at the time of image formation, the amount of electric power supplied to the photosensitive drum heater may be controlled to be strengthened for a certain period of time. Even if the amount of power supplied to the photosensitive drum heater is increased, it takes some time for the temperature of the photosensitive drum surface to rise, but image deletion may occur because multiple transfer materials are repeatedly passed. It is effective in suppressing / preventing accidents.

(2) When paper is to be passed from the multi-tray 14 of FIG. 7, when the type of transfer material input by the user, such as coated paper or OHP paper, is selected, the same as in (1) above. You can control it.

As described above, if the types of the transfer material to be stored in the plurality of transfer material storage portions are registered in advance, the type of the transfer material can be discriminated from the transfer material storage selected at the time of use,
Alternatively, since it can be determined by the information input by the user, it is possible to obtain the same effect as that of the fifth embodiment without a detection mechanism such as resistance measuring means of the transfer material.

[0077]

As described above, the first aspect of the present application
According to another aspect of the present invention, there is provided an image carrier, a charging unit that charges the image carrier, an exposure unit that imagewise exposes the charged surface of the image carrier to form an electrostatic latent image according to image information, Developing means for forming a toner image by adhering toner to the electrostatic latent image, transfer means for transferring the toner image to a transfer material at a transfer site, and an image carrier inside or near the image carrier. In the image forming apparatus having a heater for heating the heater, the amount of electric power supplied to the heater is controlled for a predetermined time after the power is turned on depending on the time when the heater is not energized.

The second aspect of the invention is to control the average amount of electric power per unit time supplied to the heater for a predetermined time after the energization is turned on according to the time when the heater is not energized. Characterize.

The third aspect of the invention is characterized in that the temperature of the heater is controlled for a predetermined time after the energization is turned on according to the time when the heater is not energized.

Further, the fourth invention is characterized in that the temperature of the heater is set higher than usual for a predetermined time after the energization is turned on in accordance with the time when the heater is not energized.

With the above structure, when the power supplied to the heater is turned on and the power to be supplied is increased, or when ON / OFF is repeatedly controlled, the ratio of the ON time is increased to supply the power per unit time. By increasing the amount, it is possible to raise the temperature of the heater, or to energize another heater that is not normally used even at the same temperature to raise the drum surface temperature faster and maintain it at a higher temperature. It will be possible. Therefore, removal of water on the surface of the photosensitive drum can be promoted, and image deletion can be prevented or suppressed.

The fifth aspect of the present invention is based on both the time when the heater is not energized and the temperature / humidity data in the vicinity of the image bearing member or inside or near the image forming apparatus, after the energization is turned on. The amount of electric power supplied to the heater for a predetermined time is controlled.

With the above configuration, the amount of electric power supplied to the heater is controlled by utilizing the temperature and humidity data inside or near the image forming apparatus. Therefore, for example, in a low humidity environment, the amount of water adhering to the surface of the photosensitive drum is small and the image flow occurs. When the power supply does not occur, the power supply amount can be controlled not to be strengthened or to be turned off. Therefore, strengthen the photosensitive drum heater only when it is necessary under temperature and humidity conditions, and turn it ON / OF.
Since the F control can be performed, it is possible to reduce wasteful power consumption and prevent adverse effects such as temperature rise in the machine.

The sixth aspect of the invention is characterized in that the temperature / humidity data is one or both of the history of the state where the energization is OFF and the time when it is turned ON.

With the above configuration, when the temperature / humidity data at the time when the energization is turned on is used, there is an advantage that the memory is unnecessary and the control can be simplified.

On the other hand, in the case of using the temperature and humidity history data in the state where the energization is OFF, a memory for storing the data and a processing process are required, but the amount of electric power supplied to the photosensitive drum heater is more appropriate. Can be controlled. For example, when the air conditioner in the room in which the image forming apparatus main body is installed is also stopped at night or on a holiday, the temperature and humidity are often high in the summer. At this time, if the air conditioner is turned on and the power of the image forming apparatus main body is turned on after a while, the amount of adsorbed water on the surface of the photosensitive drum is still changing even if the temperature and humidity are normal values. Since it is not present, image deletion may occur. In such a case, it is possible to solve it by using history data of temperature and humidity.

According to the seventh aspect of the invention, depending on the time when the heater is not energized and the type of the transfer material to be fed,
It is characterized in that the amount of electric power supplied to the heater is controlled for a predetermined time after the energization is turned on.

The occurrence state of image deletion is
It also changes depending on the type of transfer material used. Therefore, by controlling the amount of power supplied to the heater based on both of them, it is possible to minimize power consumption and adverse effects and prevent / suppress image deletion.

According to the eighth aspect of the invention, the energization is turned on depending on the combination of the time when the heater is not energized and the selected transfer material accommodating section among the plurality of transfer material accommodating sections. It controls the amount of electric power supplied to the heater for a predetermined time.

By registering the types of the transfer material to be stored in the plurality of transfer material storage portions, the type of the transfer material can be discriminated from the selected transfer material storage portion, and the above-mentioned method can be used without a mechanism for detecting the type of the transfer material. The same effect as can be obtained.

In the above description, the main purpose is to prevent image deletion in a high humidity environment, but it is also effective for stabilizing the image density. That is, since the charging performance of the photosensitive drum and the sensitivity at the time of exposure have temperature dependence, if the photosensitive drum heater is also turned on almost at the same time when the power of the image forming apparatus is turned on, the image forming state is set. However, the surface of the photosensitive drum is not yet sufficiently heated. At this time, the image density is different between when the image is formed and when the surface of the photosensitive drum is heated after that because the charging potential and the potential after exposure are different. It also appears as a difference in color in color copiers and printers.

On the other hand, in the present invention, since the surface temperature of the photosensitive drum rises quickly, the image density and color tone can be stabilized relatively quickly.

[Brief description of drawings]

FIG. 1 is a control timing sheet of a photosensitive drum heater according to a first embodiment.

FIG. 2 is a diagram showing a time transition of a photosensitive drum surface temperature according to the first and second embodiments.

FIG. 3 is a control timing chart of a main body power supply and a photosensitive drum heater according to the second embodiment.

FIG. 4 is a control timing chart of a photosensitive drum heater in a conventional image forming apparatus.

FIG. 5 is a control timing chart of the photosensitive drum heater according to the third embodiment.

FIG. 6 is a control timing chart of the photosensitive drum heater according to the fourth embodiment.

FIG. 7 is a schematic cross-sectional view of an image forming apparatus to which the related art and the present invention can be applied.

FIG. 8 is a sectional view of a photosensitive drum having a photosensitive drum heater.

FIG. 9 is a diagram showing a method of supplying power to the photosensitive drum heater.

FIG. 10 is a diagram showing an example of a pattern of a photosensitive drum heater.

[Explanation of symbols]

1 photosensitive drum 2 Primary charger 3 laser (image exposure) 4 developing device 5 Transfer charger 6 Separation charger 7 cleaner 10-12 paper cassette 20 Photosensitive drum heater 21 Temperature sensor

Claims (8)

[Claims] 1. An image bearing member, a charging unit for charging the image bearing member, and an exposing unit for exposing the charged surface of the image bearing member with an image to form an electrostatic latent image according to image information. Developing means for forming a toner image by adhering toner to the electrostatic latent image, transfer means for transferring the toner image to a transfer material at a transfer site, and image transfer means inside or near the image carrier. An image forming apparatus having a heater for heating a body, characterized in that an amount of electric power supplied to the heater is controlled for a predetermined time after the energization is turned on in accordance with a time when the heater is not energized in the previous period. Forming equipment. 2. The average amount of electric power per unit time supplied to the heater for a predetermined time after the energization is turned on is controlled according to the time during which the heater has not been energized. Image forming device. 3. The image forming apparatus according to claim 1, wherein the temperature of the heater is controlled for a predetermined time after the energization is turned on in accordance with the time when the heater is not energized. 4. The image forming method according to claim 1, wherein the temperature of the heater is set higher than usual for a predetermined time after the energization is turned on in accordance with a time when the heater is not energized. apparatus. 5. The time during which the heater is not energized,
5. The amount of electric power supplied to the heater for a predetermined time after the energization is turned on is controlled based on both temperature and humidity data in the vicinity of the image carrier or inside or near the image forming apparatus. Image forming device. 6. The image forming apparatus according to claim 1, wherein the temperature / humidity data is one or both of a history of an energized state being OFF and a time when the electricity is turned ON. 7. The time when there is no power to the heater,
7. The image forming apparatus according to claim 1, wherein the amount of electric power supplied to the heater is controlled for a predetermined time after the energization is turned on according to the type of the transfer material to be fed. 8. The time during which the heater is not energized,
The amount of electric power supplied to the heater for a predetermined time after the energization is turned on is controlled according to a combination with a transfer material storage unit selected from a plurality of transfer material storage units. 7 image forming apparatus.